Voltage regulating device and method

Abstract

This application provides a voltage regulation device and method. The voltage regulation device includes a driving circuit and a comparator circuit interconnected with each other. The driving circuit receives an initial voltage to output a first voltage and generates a second voltage based on the first voltage. The comparator circuit generates a third voltage based on the first voltage and compares the second voltage and the third voltage. When the second voltage is not equal to the third voltage, the comparator circuit outputs a feedback voltage to the driving circuit, causing the driving circuit to adjust the first voltage. The voltage regulation device and method provided by this application can effectively solve the problem of unstable output voltage, enabling the display panel to receive a stable voltage, increasing the stability of voltage output, and preventing waste caused by excessively high voltage or display abnormalities caused by excessively low voltage.

Description

Technical Field

[0001] This application relates to the field of display technology, specifically to a voltage regulation device and method. Background Technology

[0002] In the field of display panel technology, thinner cables are often chosen to reduce material procurement costs. However, thinner cables result in higher impedance and excessive voltage drop. Furthermore, unstable voltage transmitted from the customer system to the PCB (printed circuit board) can cause functional abnormalities, leading to a series of problems such as display malfunctions and severely impacting the user experience. Summary of the Invention

[0003] This application provides a voltage regulation device and method for mitigating the problem of unstable voltage received by a display panel.

[0004] In one aspect, this application provides a voltage regulation device, specifically, the voltage regulation device includes a drive circuit and a comparator circuit connected to each other.

[0005] The driving circuit receives an initial voltage to output a first voltage, and generates a second voltage based on the first voltage;

[0006] The comparison circuit generates a third voltage based on the first voltage and compares the second voltage with the third voltage. When the second voltage is not equal to the third voltage, it outputs a feedback voltage to the drive circuit, causing the drive circuit to adjust the first voltage.

[0007] Optionally, the driving circuit includes a driving chip, a first resistor, and a second resistor;

[0008] Wherein, the first pin of the driver chip receives the initial voltage, the first end of the first resistor is connected to the second pin of the driver chip to receive the first voltage, the second end of the first resistor is connected to the third pin of the driver chip and the first end of the second resistor, and the second end of the second resistor is connected to the comparator circuit.

[0009] Optionally, the driving circuit further includes a first capacitor;

[0010] The positive terminal of the first capacitor is connected to the first pin of the driver chip, and the negative terminal of the first capacitor is connected to the fourth pin of the driver chip, which is grounded.

[0011] Optionally, the driving circuit further includes a second capacitor;

[0012] The positive terminal of the second capacitor is connected to the fifth pin of the driver chip, and the negative terminal of the second capacitor is connected to the second pin of the driver chip and the first end of the first resistor.

[0013] Optionally, the driving circuit further includes an inductor;

[0014] The positive terminal of the inductor is connected to the second pin of the driver chip, and the negative terminal of the inductor is connected to the first end of the first resistor.

[0015] Optionally, the driving circuit further includes a third resistor;

[0016] The second end of the second resistor is also connected to the first end of the third resistor, and the second end of the third resistor is grounded.

[0017] Optionally, the comparison circuit includes an operational amplifier and a fourth resistor;

[0018] The first end of the fourth resistor is connected to the first end of the first resistor to receive the first voltage. The first voltage is stepped down by the fourth resistor and output to the display panel. The second end of the fourth resistor is connected to the positive input terminal of the operational amplifier. The negative input terminal of the operational amplifier is connected to the second end of the second resistor. The output terminal of the operational amplifier is connected to the first end of the second resistor to output the feedback voltage to the driving circuit.

[0019] Optionally, the comparison circuit further includes a third capacitor;

[0020] The positive terminal of the third capacitor is connected to the first end of the first resistor and the first end of the fourth resistor, and the negative terminal of the third capacitor is grounded.

[0021] Optionally, the comparison circuit further includes a fifth resistor and a sixth resistor;

[0022] The fifth resistor is connected in series between the fourth resistor and the operational amplifier;

[0023] The first end of the sixth resistor is connected to the fifth resistor and the positive input terminal of the operational amplifier to receive the third voltage, and the second end of the sixth resistor is grounded.

[0024] On the other hand, this application also provides a voltage regulation method, specifically applied to the voltage regulation device described above, comprising:

[0025] Connect the initial input voltage and set the preset feedback voltage;

[0026] The driving circuit receives an initial voltage to output a first voltage, and generates a second voltage based on the first voltage;

[0027] The comparator circuit generates a third voltage based on the first voltage and controls the operational amplifier to detect whether the second voltage and the third voltage are equal;

[0028] If the second voltage is not equal to the third voltage, the comparator circuit controls the operational amplifier to output a feedback voltage to adjust the first voltage;

[0029] If the second voltage is equal to the third voltage, and the feedback voltage is equal to the preset feedback voltage, the comparison circuit outputs a stable voltage to the display panel based on the first voltage.

[0030] As described above, the voltage regulation device and method provided in this application detect instability of the third voltage by comparing the second voltage and the third voltage and outputting a feedback voltage, thereby enabling the drive circuit to automatically adjust the first voltage so that the third voltage is output stably. Attached Figure Description

[0031] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0032] Figure 1 This is a circuit diagram of a voltage regulation device according to an embodiment of this application.

[0033] Figure 2 This is a waveform comparison diagram of the voltage adjustment of the display panel according to an embodiment of this application.

[0034] Figure 3 This is a flowchart of a voltage regulation method according to an embodiment of this application.

[0035] The realization of the objectives, functional features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. The accompanying drawings have illustrated specific embodiments of this application, which will be described in more detail below. These drawings and textual descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this application to those skilled in the art through reference to specific embodiments. Detailed Implementation

[0036] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0037] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, components, features, and elements with the same names in different embodiments of this application may have the same meaning or different meanings, the specific meaning of which must be determined by its interpretation in that specific embodiment or further in conjunction with the context of that specific embodiment.

[0038] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0039] First Embodiment

[0040] In one aspect, this application provides a voltage regulation device. Figure 1 This is a circuit diagram of a voltage regulation device according to an embodiment of this application.

[0041] Please see Figure 1 In one embodiment, the voltage regulation device includes a drive circuit 10 and a comparator circuit 20 interconnected. The drive circuit 10 receives an initial voltage to output a first voltage V1 and generates a second voltage V2 based on the first voltage V1. The comparator circuit 20 generates a third voltage V3 based on the first voltage V1 and compares the second voltage V2 and the third voltage V3. When the second voltage V2 is not equal to the third voltage V3, the comparator circuit 20 outputs a feedback voltage to the drive circuit 10, causing the drive circuit 10 to adjust the first voltage V1.

[0042] For example, when the voltage regulator is powered on or during light / heavy load switching, the third voltage V3 generated by the comparator circuit 20 will change. By comparing the second voltage V2 and the third voltage V3 and outputting a feedback voltage to detect instability in the third voltage V3, the drive circuit 10 will automatically adjust the first voltage V1 to stabilize the output of the third voltage V3. Optionally, this application does not limit the magnitudes of the first voltage V1, the second voltage V2, the third voltage V3, and the feedback voltage. The user can select suitable values ​​for the feedback voltage, the first voltage V1, the second voltage V2, and the third voltage V3 by setting the drive circuit 10 and the comparator circuit 20.

[0043] Please continue reading. Figure 1In one embodiment, the driving circuit 10 includes a driving chip 11, a first resistor R1, and a second resistor R2. The first pin of the driving chip 11 receives an initial voltage. The first end of the first resistor R1 is connected to the second pin of the driving chip 11 to receive a first voltage V1. The second end of the first resistor R1 is connected to the third pin of the driving chip 11 and the first end of the second resistor R2. The second end of the second resistor R2 is connected to the comparator circuit 20.

[0044] For example, the driver chip 11 can be a BUCK power supply chip, which steps down the initial voltage to output a first voltage V1. The first pin of the driver chip 11 is an input pin for receiving the initial voltage. The second pin of the driver chip 11 is a switch output pin for outputting the first voltage V1. The first resistor R1 and the second resistor R2 are voltage divider resistors. The third pin of the driver chip 11 is a feedback pin for receiving the feedback voltage output by the comparator circuit 20 and feeding it back to the driver chip 11. When the driver chip 11 receives a change in the feedback voltage, it adjusts the first voltage V1 output from the first pin. Optionally, this application does not limit the type of driver chip 11 or the values ​​of the first resistor R1 and the second resistor R2.

[0045] Please continue reading. Figure 1 In one embodiment, the driving circuit 10 further includes a first capacitor C1. The positive terminal of the first capacitor C1 is connected to the first pin of the driving chip 11, and the negative terminal of the first capacitor C1 is connected to the fourth pin of the driving chip 11, which is grounded.

[0046] For example, the fourth pin of the driver chip 11 is a ground pin, and the first capacitor C1 is connected between the first and fourth pins of the driver chip 11 for filtering and protection circuitry. Optionally, this application does not limit the size of the first capacitor C1.

[0047] Please continue reading. Figure 1 In one embodiment, the driving circuit 10 further includes a second capacitor C2. The positive terminal of the second capacitor C2 is connected to the fifth pin of the driving chip 11, and the negative terminal of the second capacitor C2 is connected to the second pin of the driving chip 11 and the first end of the first resistor R1.

[0048] For example, pin 5 of driver chip 11 is a startup pin, and second capacitor C2 is connected between pin 5 and pin 2 of driver chip 11. It is a bootstrap capacitor used to drive the output first voltage V1, acting as a boost charging capacitor. Optionally, this application does not limit the size of the second capacitor C2.

[0049] Please continue reading. Figure 1 In one embodiment, the driving circuit 10 further includes an inductor L. The positive terminal of the inductor L is connected to the second pin of the driving chip 11, and the negative terminal of the inductor L is connected to the first end of the first resistor R1.

[0050] For example, an inductor L is connected in series between the first resistor R1 and the second pin of the driver chip 11 to store and release energy when the first pin is switched, thus serving as a freewheeling current. The driver chip 11 also includes a sixth pin, which is an enable control pin. Optionally, this application does not limit the size of the inductor L.

[0051] Please continue reading. Figure 1 In one embodiment, the driving circuit 10 further includes a third resistor R3. The second end of the second resistor R2 is also connected to the first end of the third resistor R3, and the second end of the third resistor R3 is grounded.

[0052] For example, the third resistor R3 is a voltage divider resistor. Optionally, this application does not limit the size of the third resistor R3.

[0053] Please continue reading. Figure 1 In one embodiment, the comparator circuit 20 includes an operational amplifier D and a fourth resistor R4. The first terminal of the fourth resistor R4 is connected to the first terminal of the first resistor R1 to receive a first voltage V1, the second terminal of the fourth resistor R4 is connected to the positive input terminal of the operational amplifier D, the negative input terminal of the operational amplifier D is connected to the second terminal of the second resistor R2, and the output terminal of the operational amplifier D is connected to the first terminal of the second resistor R2 to output a feedback voltage to the drive circuit 10.

[0054] For example, the fourth resistor R4 represents the line resistance between the drive circuit 10 and the adjustment circuit. The first voltage V1 is stepped down through the fourth resistor R4 to output a voltage to the display panel. Optionally, this application does not limit the type of display panel; the display panel can be a PCB board, and the output voltage is the PCB voltage V-PCB. Optionally, this application does not limit the size of the fourth resistor R4; the fourth resistor R4 represents the connection relationship between the user system terminal and the display panel and is a variable resistor. Operational amplifier D is used to balance the third voltage V3 at the positive input terminal and the second voltage V2 at the negative input terminal. Understandably, the negative input terminal of operational amplifier D is connected between the second resistor R2 and the third resistor R3, and the second voltage V2 is the voltage across the third resistor R3. The output terminal of operational amplifier D is connected between the second resistor R2 and the first resistor R1, and the feedback voltage is the voltage across the second resistor R2 and the third resistor R3. When the operational amplifier D outputs a feedback voltage, it is directly fed back to the driver chip 11. The driver chip 11 continuously adjusts the first voltage V1 to make the third voltage V3 equal to the second voltage V2, and makes the voltage across the second resistor R2 and the third resistor R3 equal to the preset feedback voltage, thereby forming a closed-loop negative feedback so that the voltage output to the display panel through the fourth resistor can be stably output.

[0055] Please continue reading. Figure 1In one embodiment, the comparator circuit 20 further includes a third capacitor C3. The positive terminal of the third capacitor C3 is connected to the first terminal of the first resistor R1 and the first terminal of the fourth resistor R4, and the negative terminal of the third capacitor C3 is grounded.

[0056] For example, the third capacitor C3 is a grounding capacitor used to filter the first voltage V1. Optionally, this application does not limit the size of the third capacitor C3.

[0057] Please continue reading. Figure 1 In one embodiment, the comparator circuit 20 further includes a fifth resistor R5 and a sixth resistor R6. The fifth resistor R5 is connected in series between the fourth resistor R4 and the operational amplifier D. The first terminal of the sixth resistor R6 is connected to the fifth resistor R5 and the positive input terminal of the operational amplifier D to receive the third voltage V3, and the second terminal of the sixth resistor R6 is grounded.

[0058] For example, the fifth resistor R5 and the sixth resistor R6 are voltage divider resistors. The positive input terminal of the operational amplifier D is connected between the fifth resistor R5 and the sixth resistor R6, and the third voltage V3 is the voltage across the sixth resistor R6. Optionally, this application does not limit the values ​​of the fifth resistor R5 and the sixth resistor R6.

[0059] In one embodiment, taking the first resistor R1 = 30KΩ, the second resistor R2 = 14KΩ, the third resistor R3 = 21KΩ, the fifth resistor R5 = 38KΩ, the sixth resistor R6 = 28KΩ, and the preset feedback voltage FB = 2.34V as an example, the voltage output through the fourth resistor is the PCB voltage V-PCB.

[0060] In the initial state, the driver circuit 10 and the comparator circuit 20 are not connected. The operational amplifier D and the fourth resistor R4 are not connected to the driver circuit 10, and the feedback mechanism of the driver chip 11 has not yet been activated. Assuming that the first voltage V1 output by the driver circuit 10 is 3.3V at this time, the second voltage V2 = V1*R3 / (R1+R2+R3) = 1.07V, the third voltage V3 = 0V, the operational amplifier D is in the off state, and no feedback voltage is output at the output terminal.

[0061] If the driver circuit 10 and the comparator circuit 20 are connected, the operational amplifier D and the fourth resistor R4 are connected to the driver circuit 10. Assume that after the circuit is turned on, the PCB voltage V-PCB is 2.8V, meaning the voltage of the first voltage V1 through the fourth resistor R4 is 2.8V. Then, the third voltage V3 = V-PCB * R6 / (R5 + R6) = 1.19V. The third voltage V3 is not equal to the second voltage V2, triggering the feedback mechanism. The operational amplifier D outputs a feedback voltage of 1.19V. Since 1.19V is not equal to 2.34V, the driver chip 11 continuously adjusts the first voltage V1. When the PCB voltage V-PCB is 3.3V, the third voltage V3 = 1.4V. At this time, the second voltage V2 = 1.4V, the output of the operational amplifier D is not outputting. The voltage across the second resistor R2 and the third resistor R3 is 2.34V, equal to the preset feedback voltage, thus maintaining the PCB voltage V-PCB at a stable state of 3.3V.

[0062] Second Embodiment

[0063] On the other hand, this application also provides a display panel, specifically including the voltage regulation device as described above.

[0064] For example, the power supply system outputs an initial voltage to the voltage regulator in the display panel, and the voltage regulator receives the initial voltage and stabilizes the output voltage so that the display panel can work stably.

[0065] Figure 2 This is a waveform comparison diagram of the voltage adjustment of the display panel according to an embodiment of this application.

[0066] Please see Figure 2 For example, the display panel is a PCB board. Before the improvement, when the output first voltage V1 is 3.3V, the PCB board receives a PCB voltage V-PCB of 3V, which drops under heavy load, failing to meet the operating requirements of the circuit board. After the improvement, when the output first voltage V1 is 3.3V, the PCB board receives a PCB voltage V-PCB of 2.8V, which also fails to meet the operating requirements of the PCB board. In this case, the voltage adjustment device adjusts the first voltage V1 to 3.6V so that the PCB board receives a PCB voltage V-PCB of 3.3V. When the display panel experiences a light-load / heavy-load switch, it will not affect the circuit board's stable reception of a 3.3V PCB voltage V-PCB.

[0067] Third Embodiment

[0068] On the other hand, this application also provides a voltage regulation method. Figure 3 This is a flowchart of a voltage regulation method according to an embodiment of this application.

[0069] Please see Figure 3In one embodiment, the voltage regulation method is applied to the voltage regulation device as described above, comprising:

[0070] An initial input voltage is used to obtain a first voltage through the drive circuit, and a preset feedback voltage is set. A first resistor outputs voltage to the display panel via a line resistor. The display panel includes a PCB board, and the output voltage is the PCB voltage. An operational amplifier detects whether a third voltage V3 and a second voltage V2 are equal. If they are equal, the PCB board directly outputs the PCB voltage. If they are not equal, the operational amplifier outputs a feedback voltage equal to V3, thereby continuously adjusting the first voltage until V3 equals V2. Adjustment stops when the feedback voltage equals the preset feedback voltage, resulting in a stable PCB voltage output.

[0071] As described above, the voltage regulation device and method provided in this application can effectively solve the problem of unstable output voltage, enabling the PCB board to receive a stable voltage and increasing the stability of the voltage output. This prevents waste caused by excessively high voltage or display abnormalities caused by excessively low voltage.

[0072] The embodiments of the display panel provided in this application may include all the technical features of any of the above-described method embodiments. The extended and explanatory content of the specification is basically the same as that of the embodiments of the above methods, and will not be repeated here.

[0073] This application also provides a computer program product, which includes computer program code. When the computer program code is run on a computer, it causes the computer to perform the methods described in the various possible implementations above.

[0074] This application also provides a chip, including a memory and a processor. The memory is used to store a computer program, and the processor is used to call and run the computer program from the memory, so that a device with the chip installed performs the methods described in the various possible implementations above.

[0075] It is understood that the above scenarios are merely examples and do not constitute a limitation on the application scenarios of the technical solutions provided in the embodiments of this application. The technical solutions of this application can also be applied to other scenarios. For example, as those skilled in the art will know, with the evolution of system architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0076] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0077] The steps in the method of this application embodiment can be adjusted, combined, or deleted according to actual needs.

[0078] The units in the device of this application embodiment can be merged, divided, and deleted according to actual needs.

[0079] In this application, the same or similar terms, concepts, technical solutions and / or application scenario descriptions are generally described in detail only when they appear for the first time. When they appear again, they are generally not repeated for the sake of brevity. When understanding the technical solutions and other contents of this application, the same or similar terms, concepts, technical solutions and / or application scenario descriptions that are not described in detail later can be referred to their previous relevant detailed descriptions.

[0080] In this application, the descriptions of the various embodiments have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0081] The technical features of the present application can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of the present application.

[0082] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A voltage regulating device, characterized in that, Applied to a display panel, the voltage regulation device includes a drive circuit and a comparator circuit connected to each other; The driving circuit receives an initial voltage to output a first voltage, and generates a second voltage based on the first voltage; The comparison circuit generates a third voltage based on the first voltage and compares the second voltage with the third voltage. When the second voltage is not equal to the third voltage, it outputs a feedback voltage to the drive circuit, causing the drive circuit to adjust the first voltage. The driving circuit includes a driving chip, a first resistor, a second resistor, and a third resistor. The first pin of the driving chip is used to receive the initial voltage, the second pin of the driving chip is a switch output pin used to output the first voltage, and the third pin of the driving chip is a feedback pin used to receive the feedback voltage output by the comparator circuit and feed it back to the driving chip. The first end of the first resistor is connected to the second pin of the driver chip to receive the first voltage. The second end of the first resistor is connected to the third pin of the driver chip and the first end of the second resistor. The second end of the second resistor is connected to the first end of the third resistor. The second end of the third resistor is grounded. The feedback voltage is the voltage across the second resistor and the third resistor. The comparator circuit includes an operational amplifier, a fourth resistor, a fifth resistor, and a sixth resistor. The first terminal of the fourth resistor is connected to the first terminal of the first resistor to receive the first voltage. The fourth resistor simulates the line impedance between the driving circuit and the display panel. The first voltage is stepped down by the fourth resistor and output to the display panel. The fifth resistor is connected in series between the second terminal of the fourth resistor and the positive input terminal of the operational amplifier. The first terminal of the sixth resistor is connected to the fifth resistor and the positive input terminal of the operational amplifier. The second terminal of the sixth resistor is grounded. The third voltage is the voltage across the sixth resistor. The negative input terminal of the operational amplifier... The second terminal of the second resistor is connected to receive the second voltage; the second voltage is the voltage across the third resistor; the output terminal of the operational amplifier is connected to the first terminal of the second resistor to output the feedback voltage to the third pin of the driver chip; when the second voltage is not equal to the third voltage, the operational amplifier outputs a feedback voltage to the third pin of the driver chip, so that the driver chip continuously adjusts the first voltage, making the third voltage and the second voltage equal, and the feedback voltage across the second resistor and the third resistor equal to a preset feedback voltage, thereby forming a closed-loop negative feedback, so that the voltage output to the display panel through the fourth resistor can be stably output.

2. The voltage regulating device as described in claim 1, characterized in that, The driving circuit also includes a first capacitor; The positive terminal of the first capacitor is connected to the first pin of the driver chip, and the negative terminal of the first capacitor is connected to the fourth pin of the driver chip, which is grounded.

3. The voltage regulating device as described in claim 1, characterized in that, The driving circuit also includes a second capacitor; The positive terminal of the second capacitor is connected to the fifth pin of the driver chip, and the negative terminal of the second capacitor is connected to the second pin of the driver chip and the first end of the first resistor.

4. The voltage regulating device as described in claim 1, characterized in that, The driving circuit also includes an inductor; The positive terminal of the inductor is connected to the second pin of the driver chip, and the negative terminal of the inductor is connected to the first end of the first resistor.

5. The voltage regulating device as described in claim 1, characterized in that, The comparison circuit also includes a third capacitor; The positive terminal of the third capacitor is connected to the first end of the first resistor and the first end of the fourth resistor, and the negative terminal of the third capacitor is grounded.

6. A voltage regulation method, characterized in that, Applied to the voltage regulating device as described in any one of claims 1-5, comprising: Input the initial voltage and set the preset feedback voltage; The driving circuit receives an initial voltage to output a first voltage, and generates a second voltage based on the first voltage; The comparator circuit generates a third voltage based on the first voltage and controls the operational amplifier to detect whether the second voltage and the third voltage are equal; If the second voltage is not equal to the third voltage, the comparator circuit controls the operational amplifier to output a feedback voltage to adjust the first voltage; If the second voltage is equal to the third voltage, and the feedback voltage is equal to the preset feedback voltage, the comparison circuit outputs a stable voltage to the display panel based on the first voltage.

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